A specific and obligatory role for long chain polyenoic acids (LCPA) in spermatogenesis is suggested by several lines of evidence. Our objective is to elucidate that role with initial emphasis on 1) localization of LCPA and lipids containing them to specific classes of cells and structures in which they play their role, 2) description of LCPA metabolism, transport and uptake with respect to cell type and stage of spermatogenesis, which will reflect mechanisms of accumulation and possible functions, 3) determination of effects of testis maturation and effectors of spermatogenesis on distribution of LCPA concentration, metabolism and uptake, in order to elucidate the nature of correlations between LCPA and state of spermatogenesis and the roles of the effectors. Prerequisite to reaching these objectives is the enabling objective, separation of the testis cell population into specific cell types and stages of differentiation. We will sort single cell suspensions of mouse testis into component cell types and stages by electronic cell sorting on the basis of light scatter and fluorescence of viable stains. We will use mechanical, isopycnic or isokinetic separations as preenrichment procedures to increase yields. We will quantitate LCPA and other fatty acids in purified cells and in specific complex lipids using gas chromatography and high performance liquid chromatography (HPLC). We will measure biosynthesis, catabolism, retroconversion and uptake of LCPA by monitoring in vivo and in vitro radioisotope incorporation into cells and component lipids with liquid scintillation counting and gas radiochromatography. We will sort cells from immature testis and testis of mice treated by various dietary, chemical and physical interventions to determine the effects of modification of spermatogenesis on patterns of LCPA distribution, uptake and metabolism. These studies will further our understanding of testicular differentiation and spermatogenesis.